Lenovo's K3 Note is now picking up the Marshmallow update in India. The update — weighing in at 1.65GB — brings Doze, advanced app permissions, Google Now on Tap, and March's security updates. Also included is TheaterMax support for VR, which makes the K3 Note compatible with Lenovo's AntVR viewer.
Lenovo's official update tracker is yet to confirm the update for more recent launches like the K4 Note and the Vibe X3, but we'll let you know once it becomes available. If you're unable to download the OTA update for the K3 Note, you can grab the files from here and manually flash using recovery.